Power module and power conversion system including same

ABSTRACT

A power module includes an upper substrate comprising a plurality of circuit pattern areas made of a metal and a dielectric area disposed between each of the plurality of circuit pattern areas; a lower substrate including a plurality of circuit pattern areas made of a metal and a dielectric area disposed between each of the plurality of circuit pattern areas; and a semiconductor element having an upper terminal and a lower terminal, the upper terminal and the lower terminal being bonded to a lower surface of the upper substrate and an upper surface of the lower substrate, respectively.

CROSS REFERENCE TO RELATED APPLICATION

The present application claims the benefit of priority to Korean PatentApplication No. 10-2017-0100413, filed on Aug. 8, 2017 in the KoreanIntellectual Property Office, the entirety of which is incorporatedherein for all purposes by this reference.

TECHNICAL FIELD

The present disclosure relates to a power module and a power conversionsystem including the same and, more specifically, a power module and apower conversion system including the same, in which dielectric materialcoating is applied to an area other than a Surface Mount Technology(SMT) area and a dielectric material is inserted in a pore between leadframe patterns to enable lead frames to have an integrated structure, sothat the power module can have a 2-in-1, 4-in-1, or 6-in-1 structure inwhich multiple semiconductors can be mounted on one substrate.

BACKGROUND

A power conversion system (e.g. inverter) is one of the core componentsof hybrid vehicles and electric vehicles, and a major component for anenvironmentally friendly vehicle. Many technologies regarding the powerconversion system have been developed and a technology for developing apower module is being developed. The power module is a core component ofthe power conversion system and has the highest cost of production amongcomponents of the power conversion system, and is a core technology inthe field of environmentally friendly vehicles.

The power module may be an insulated-type power module or anon-insulated-type power module. A conventional non-insulated-type powermodule uses a single lead frame and thus there may be difficulty informing a pattern. Therefore, the conventional non-insulated-type powermodule allows design of a 1-in-1 or 2-in-1 structure but requires acomplicated configuration for the lead frame in the case of expansion toa 4-in-1 or 6-in-1 structure, which makes it difficult to expand thestructure design of the power module.

Further, an insulated-type two-layered Thermal Interface Material (TIM)and an insulated-type one-layered Si₃N₄ ceramic substrate may be appliedin order to configure the conventional non-insulated-type power module.Thus, the conventional non-insulated-type power module has adeteriorated heat-radiation property.

Further, the conventional non-insulated-type power module is configuredin a multi-layered solder structure due to the application of a spacerthereto and thus has reduced reliability. The conventionalnon-insulated-type power module requires multiple processes to beapplied thereto due to wire bonding and thus needs to ensure thereliability of the wire bonding.

Therefore, there has been a demand for a solution which can develop thepower module into an expanded type, can improve a heat-radiationproperty, and can implement a simplified structure for reliabilityimprovement and process improvement.

The above information disclosed in this Background section is only forenhancement of understanding of the background of the present disclosureand should not be taken as acknowledgement that this information formsthe prior art that is already known to a person skilled in the art.

SUMMARY

The present disclosure has been proposed to solve the above-describedproblems, and an aspect of the present disclosure provides a powermodule and a power conversion system including the same, in whichdielectric material coating is applied to an area other than an SMT areaand a dielectric material is inserted in a pore between lead framepatterns to enable lead frames to have an integrated structure, so thatthe power module can have a 2-in-1, 4-in-1, or 6-in-1 structure in whichmultiple semiconductors can be mounted on one substrate.

In order to achieve the above-described aspect, a power module accordingto the present disclosure may include: an upper substrate including aplurality of circuit pattern areas made of a metal and a dielectric areadisposed between each of the plurality of circuit pattern areas; a lowersubstrate including a plurality of circuit pattern areas made of a metaland a dielectric areas disposed between each of the plurality of circuitpattern areas; and a semiconductor element having an upper terminal anda lower terminal, the upper terminal and the lower terminal being bondedto the lower surface of the upper substrate and the upper surface of thelower substrate, respectively.

The power module may further include a dielectric layer disposed betweenthe upper substrate and the lower substrate, wherein the dielectriclayer has an opening formed in an area in which the upper substrate andthe lower substrate are electrically connected to each other or in anarea in which the upper substrate and the semiconductor element arebonded.

The dielectric layer may be coated on the upper surface of the lowersubstrate.

The dielectric layer may have a conductive lead formed on the uppersurface thereof and may include at least on conductive via hole forelectrically connecting the conductive lead and the semiconductorelement.

The dielectric layer may include 3-40 wt % of an epoxy compound and50-95 wt % of a ceramic, based on a total weight of the dielectriclayer.

The lower surface of the upper substrate may have an embossed portionformed thereon, the embossed portion being formed on at least a part ofeach of the plurality of circuit pattern areas, and the upper surface ofthe lower substrate may have an engraved portion formed thereon, theengraved portion being formed on at least a part of each of theplurality of circuit pattern areas.

The semiconductor element may have an upper terminal and a lowerterminal which are bonded to the embossed portion and the engravedportion, respectively.

The engraved portion may have a depth formed such that the level of theupper surface of the semiconductor element is substantially identical tothe level of the upper surface of the lower substrate on which theengraved portion is not formed.

The power module may further include a dielectric layer formed on theupper surface of the upper substrate or on the lower surface of thelower substrate.

A power conversion system according to the present disclosure mayinclude: the power module; and a cooler configured to be in surfacecontact with the dielectric layer.

The dielectric layer may include 3-40 wt % of an epoxy compound and50-95 wt % of a ceramic, based on a total weight of the dielectriclayer.

According to the power module and the power conversion system includingthe same according to various embodiments of the present disclosure,dielectric material coating is applied to an area other than an SMT areaand a dielectric material is inserted in a pore between lead framepatterns to enable lead frames to have an integrated structure, so thatthe power module can have a 2-in-1, 4-in-1, or 6-in-1 structure in whichmultiple semiconductors can be mounted on one substrate.

Further, in the power module and the power conversion system includingthe same according to various embodiments of the present disclosure, itis possible to form a part, on which a semiconductor element is to bemounted, on the same planar surface as that of a lead frame in anengraving manner and to form an embossed pattern on the upper substrate,thereby removing a spacer and simplifying the structure of a verticalconnection between lead frames.

Further, in the power module and the power conversion system accordingto various embodiments of the present disclosure, a dielectric materialexcluding a ceramic can be applied to bonding of the power module toprevent use of conventional thermal grease, which may deteriorate thethermal properties of the device. Therefore, the present disclosureprovides a power module and power conversion system with improvedbonding heat-radiation properties, allowing for an improved insulationproperty, so as to configure the power module having an improved coolingproperty.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features and advantages of the presentdisclosure will be more apparent from the following detailed descriptiontaken in conjunction with the accompanying drawings, in which:

FIG. 1 illustrates the structure of an upper substrate of a power moduleaccording to an embodiment of the present disclosure;

FIG. 2 illustrates the structure of a lower substrate of the powermodule according to an embodiment of the present disclosure;

FIG. 3 illustrates the structure of the power module according to anembodiment of the present disclosure; and

FIG. 4 illustrates the structure of a power conversion system includingthe power module according to an embodiment of the present disclosure.

DETAILED DESCRIPTION

Hereinafter, a description will be made of a power module and a powerconversion system including the same according to various embodiments ofthe present disclosure.

FIG. 1 illustrates the structure of an upper substrate of a power moduleaccording to an embodiment of the present disclosure. FIG. 2 illustratesthe structure of a lower substrate of the power module according to anembodiment of the present disclosure. FIG. 3 illustrates the structureof the power module according to an embodiment of the presentdisclosure. FIG. 4 illustrates the structure of a power conversionsystem including the power module according to an embodiment of thepresent disclosure.

First, referring to FIGS. 1 to 3, the power module according to anembodiment of the present disclosure may include: an upper substrate 100including a plurality of circuit pattern areas made of a metal and adielectric area disposed between each of the plurality of circuitpattern areas; a lower substrate 300 including a plurality of circuitpattern areas made of a metal and a dielectric area disposed betweeneach of the plurality of circuit pattern areas; and a semiconductorelement 500 having an upper terminal and a lower terminal, which arebonded to the lower surface of the upper substrate 100 and the uppersurface of the lower substrate 300, respectively.

The upper substrate 100 includes a plurality of circuit pattern areasmade of a metal and a dielectric area 130 disposed between each of theplurality of circuit pattern areas, wherein an embossed portion 10 maybe formed on at least a part of each of the plurality of circuit patternareas.

Here, the metal may be Cu. Referring to FIG. 1, the plurality of circuitpattern areas are metallic areas having a predetermined patternstructure. A process of forming a pattern is widely known and adescription thereof will be thus omitted. A space between the circuitpattern areas made of the metal corresponds to a pore. A dielectricmaterial, which is a dielectric, is inserted in the pore to constitutethe dielectric area 130. The dielectric of the dielectric area 130 is anorganic-inorganic composite dielectric material and includes 3-40 wt %of an epoxy-based resin and 50-95 wt % of a ceramic, based on a totalweight of the dielectric layer. Here, boron nitride or the like may beused as the ceramic. A dielectric material having the above-describedcomposition may be pressed and bonded at a low temperature of about 180°C., and may have low thermal stress after being bonded and may haveexcellent elasticity and toughness to prevent the same from being brokendue to a difference in thermal expansivity. The dielectric area 130,i.e., the dielectric area 130 formed by a dielectric material insertedbetween lead frames, can enlarge a heat-radiation area, and thedielectric material may have thermal conductivity of 20-50 W/mK and maythus enable heat to be transferred in the horizontal direction.

The embossed portion 10 of the upper substrate 100 may be formed in anetching manner.

The embossed portion 10 is formed on one surface of a metallic circuitpattern area (the lower surface of the upper substrate 100) so as to bedirectly soldered 50 to the semiconductor element 500 and the lowersubstrate 300 which will be described hereafter. Through this structure,a conventional spacer having low reliability can be removed.

Referring to FIG. 2, the lower substrate 300 includes a plurality ofcircuit pattern areas made of a metal and a dielectric area 330 disposedbetween each of the plurality of circuit pattern areas, wherein anengraved portion 30 may be formed on at least a part of each of theplurality of circuit pattern areas.

Here, the metal may be Cu identical to the metal of the upper substrate100. Further, the plurality of circuit pattern areas may be identical tothe plurality of circuit pattern areas of the upper substrate 100 andmay be metallic areas having a predetermined pattern structure. Like thedielectric area 130 of the upper substrate 100, the dielectric area 330may also be an area formed by a dielectric material inserted in a porebetween the circuit pattern areas made of the metal. Further, thedielectric of the dielectric area 330 may be the same as that of thedielectric area 130 of the upper substrate 100 and may be anorganic-inorganic composite dielectric material. As described above, thedielectric area 130, i.e., a dielectric material inserted between leadframes, can enlarge the heat-radiation area, and the dielectric materialmay have thermal conductivity of 20-50 W/mK and thus may enable heat tobe transferred in the horizontal direction. Further, by forming thedielectric material insertion integrated lead frame structure, a 2-in-1,4-in-1, or 6-in-1 structure, which allows multiple semiconductorelements 500 described hereafter to be mounted on one substrate alltogether, can be used.

Hereinafter, dielectrics of dielectric layers 400 and 700 (illustratedin FIGS. 2 to 4), described later, may be an organic-inorganic compositedielectric material identical to those of the upper substrate 100 andthe lower substrate 300.

A process of forming the lower substrate 300 will be briefly describedbefore the structure of the lower substrate 300 in FIG. 2 is described.First, a dielectric, i.e., a dielectric material, is coated on the uppersurface of the lower substrate 300 to form a dielectric layer 400. Thedielectric, i.e., the dielectric material is inserted in a pore betweenthe circuit pattern areas so that lead frames are integrated. Further,an engraved portion 30 of the lower substrate 300 is formed in anetching manner, and, when only a part on which the engraved portion 30is formed is removed from the dielectric layer 400 formed on the uppersurface of the lower substrate 300, the structure of the lower substrate300 is formed as illustrated in FIG. (the drawing does not include a topplan view but, in relation to a dotted line part in FIG. 2, thedielectric layer 400 of the engraved portion 30, on which thesemiconductor element 500 is to be mounted, is removed and the remainingpart, on which the semiconductor element 500 is not to be mounted, hasthe dielectric layer 400 formed thereon). Next, referring to FIG. 3, alower terminal of the semiconductor element 500 is bonded to theengraved portion 30 of the lower substrate 300 by soldering (40). Inthis case, the depth of the engraved portion 30 of the lower substrate300 may be formed such that the level of the upper surface of thesemiconductor element bonded to the engraved portion 30 is substantiallyidentical to the level of the upper surface of lower substrate 300 onwhich the engraved portion is not formed. In other words, thesemiconductor element 500 may be disposed such that the upper surface ofthe semiconductor element 500 is positioned at ±50 um level withreference to the upper surface of the lower substrate 300 on which theengraved portion 30 is not formed and thus forms substantially the sameplane. Through this structure, the upper substrate 100, the lowersubstrate 300, and the semiconductor element 500 can be directlysoldered together. Therefore, a spacer included in the conventionalpower module can be removed so as to minimize a solder layer which haslow reliability.

Referring to FIG. 3, the power module further includes a dielectriclayer 400 disposed between the upper substrate 100 and the lowersubstrate 300, wherein the dielectric layer 400 may have an opening inan area 50 in which the upper substrate 100 and the lower substrate 300are electrically connected to each other or in an area 50 in which theupper substrate and the semiconductor element are bonded.

Here, the opening is a hole formed through a part of the dielectriclayer 400 on the upper surface of the lower substrate 300, described asabove, wherein the engraved portion 30 is formed on the part of thedielectric layer 400. Solder is inserted in the opening so as todirectly solder the upper substrate 100 and the lower substrate 300 ontothe semiconductor element 500. Through this soldering, the uppersubstrate 100 and the lower substrate 300 are electrically connected, anupper terminal of the semiconductor element 500 is bonded to theembossed portion 10 of the upper substrate 100, and a lower terminalthereof is bonded to the engraved portion 30 of the lower substrate 300.The direct soldering of the embossed portion 10 of the upper substrate100 and the engraved portion 30 of the lower substrate 300 onto thesemiconductor element 500 can simplify the structure of a verticalconnection between lead frames.

Referring to FIG. 4, the power module may further include a dielectriclayer 700 formed on the upper surface of the upper substrate 100 or onthe lower surface of the lower substrate 300.

Here, the dielectric may be the same as the above-described dielectricof the dielectric area 130 of the upper substrate 100 and may be anorganic-inorganic composite dielectric material.

The dielectric layer 700 is a part in contact with a cooling means 800and has a structure for replacing a conventional structure of ThermalInterface Material (TIM)+Si₃N₄+Thermal Interface Material (TIM). Thisstructure can prevent use of thermal grease, which is mainly used as aTIM having a deteriorated thermal property, and thus can improve thebonding property and heat-radiation property of the substrate. Further,this structure can ensure even an insulation property, so as toconfigure a power module to have an improved cooling property.

Referring to FIG. 4, a conductive lead 600 is formed on the uppersurface of the dielectric layer 400 on the upper surface of the lowersubstrate 300, and the dielectric layer 400 may include at least onconductive via hole 430 for electrically connecting the conductive lead600 and the semiconductor element 500.

Here, the conductive lead 600 is electrically connected to thesemiconductor element 500 by a solder which is inserted in the via hole430 formed through the dielectric layer 400. Further, as an embodimentof the present disclosure, the conductive lead 600 may form a signalportion and metallic circuit pattern areas of the upper substrate 100and of the lower substrate 300 may form power portions.

Referring to FIG. 4, a power conversion system according to anembodiment of the present disclosure may include: a power module; and acooling means 800 configured to be in surface contact with thedielectric layer 700.

Here, the power module may include an upper substrate 100, a lowersubstrate 300, and a semiconductor element 500, which have thestructures according to the present disclosure, respectively, and may bea power module to which an epoxy molding compound (EMC) is applied as afiller 900. The cooler 800 may be a powered cooling device or a coolingchannel.

As described above, in the power module and the power conversion systemincluding the same according to various embodiments of the presentdisclosure, dielectric material coating is applied to an area other thanan SMT area and a dielectric material is inserted in a pore between leadframe patterns to enable lead frames to have an integrated structure, sothat the power module can have a 2-in-1, 4-in-1, or 6-in-1 structure inwhich multiple semiconductors can be mounted on one substrate.

Further, in the power module and the power conversion system includingthe same according to various embodiments of the present disclosure, itis possible to form a part, on which a semiconductor element is to bemounted, on the same planar surface as that of a lead frame in anengraving manner and to form an embossed pattern on the upper substrate,thereby removing a spacer and simplifying the structure of a verticalconnection between lead frames.

Further, in the power module and the power conversion system accordingto various embodiments of the present disclosure, a dielectric materialexcluding a ceramic can be applied to bonding of the power module toprevent use of conventional thermal grease, which has a deterioratedthermal property. Therefore, the power module and the power conversionsystem can improve a bonding property and a heat-radiation property andensure even an insulation property, so as to configure the power modulehaving a more excellent cooling property.

The present disclosure has been illustrated and described with referenceto particular embodiments thereof. However, it would be obvious to aperson skilled in the art that various modifications and changes arepossible within the technical idea of the present disclosure, providedby the accompanying claims.

What is claimed is:
 1. A power module comprising: an upper substratecomprising a plurality of circuit pattern areas made of a metal and adielectric area disposed in at least one of areas between the pluralityof circuit pattern areas; a lower substrate including a plurality ofcircuit pattern areas made of a metal and a dielectric area disposed inat least one of areas between the plurality of circuit pattern areas;and a semiconductor element having an upper terminal and a lowerterminal, the upper terminal and the lower terminal being bonded to alower surface of the upper substrate and an upper surface of the lowersubstrate, respectively.
 2. The power module of claim 1, furthercomprising a dielectric layer disposed between the upper substrate andthe lower substrate, wherein the dielectric layer has an opening formedin an area in which the upper substrate and the lower substrate areelectrically connected to each other or in an area in which the uppersubstrate and the semiconductor element are bonded.
 3. The power moduleof claim 2, wherein the dielectric layer is coated on the upper surfaceof the lower substrate.
 4. The power module of claim 3, wherein thedielectric layer has a conductive lead formed on the upper surfacethereof and comprises at least one conductive via hole for electricallyconnecting the conductive lead and the semiconductor element.
 5. Thepower module of claim 1, wherein the dielectric layer comprises 3-40 wt% of an epoxy compound and 50-95 wt % of a ceramic, based on a totalweight of the dielectric layer.
 6. The power module of claim 2, whereinthe dielectric layer comprises 3-40 wt % of an epoxy compound and 50-95wt % of a ceramic, based on a total weight of the dielectric layer. 7.The power module of claim 1, wherein the lower surface of the uppersubstrate has an embossed portion formed thereon, the embossed portionbeing formed on at least a part of each of the plurality of circuitpattern areas, and the upper surface of the lower substrate has anengraved portion formed thereon, the engraved portion being formed on atleast a part of each of the plurality of circuit pattern areas.
 8. Thepower module of claim 7, wherein the semiconductor element has an upperterminal and a lower terminal which are bonded to the embossed portionand the engraved portion, respectively.
 9. The power module of claim 8,wherein the level of the upper surface of the semiconductor element issubstantially identical to the level of the upper surface of the lowersubstrate on which the engraved portion is not formed.
 10. The powermodule of claim 1, further comprising a dielectric layer formed on theupper surface of the upper substrate or on the lower surface of thelower substrate.
 11. A power conversion system comprising: the powermodule set forth in claim 10; and a cooler configured to be in surfacecontact with the dielectric layer.
 12. The power conversion system ofclaim 11, wherein the dielectric layer comprises 3-40 wt % of an epoxycompound and 50-95 wt % of a ceramic, based on a total weight of thedielectric layer.